- Steel Digester Covers



Ovivo provides a wide variety of steel digester covers: Fixed, Gasholder, Hydroseal or Buoyant. Our digester steel covers are radial beam designed to be erected quickly and efficiently on site and offer a rugged structural design. A thrust ring is installed at the periphery of each cover to absorb all loads without transmitting excessive forces to the concrete digester wall.

  • Biogas and odor containment
  • Low acquisition and installation cost
  • Long, trouble-free life
  • Variable sludge storage capabilities
  • Easy operation and maintenance

The steel covers are an affordable and durable option for anaerobic digesters and/or biogas containment. These are available for tank diameters of different ranges and custom engineered to meet the customer’s requirements and needs, based on a wide variety of industry standards and proven design.

  • Simple, rugged structural design
  • Prefabricated roof sections available, for an easy and faster field installation
  • Easy to insulate, using commonly available roofing materials
  • No moving parts for simplified maintenance


The use of radial beams, and prefabricated roof sections for most of Ovivo’s projects allow for easier and faster field installation. During erection, covers are usually supported by radial beams attached to a center ring and the thrust ring, which add strength to the complete unit.

Ovivo’s cover design is compatible with all mixing systems to ensure an adequate anaerobic digestion process.

Trust Ovivo and our experienced staff. Leverage our track record for your digester cover applications. Our installation list counts more than 1,000 projects in North America alone, with sizes up to 125 feet in diameter!

Ovivo’s radial beam design can be supplied for the following configuration: Fixed, Gasholder, HydroSeal® type and Buoyant. Ovivo will provide the best option for each application based on our customer’s needs.

Ovivo® Fixed Steel Cover (Type F)
The Ovivo Type F fixed steel cover is the most economical cover available. The most common application is on digesters with constant water level (primary or first stage digesters). Fixed covers can be sealed against the tank to combat odors.

Ovivo® Gasholder (Type GV)
The Ovivo Type GV cover uses a radial beam design structure with added side sheets and ballasts for digester gas storage or flotation. Submerged ballast blocks are typically used to maximize cover stability and maintain adequate gas pressure. The design includes a vertical guide arrangement with tracks attached to the tank wall. Guide devices, spanning from the top to the bottom of the cover side sheet, are engaged to stabilize the cover.

HydroSeal® Steel Cover (Type GVL)
The use of a separate launder and liquid seal between the digester tank and the cover in the HydroSeal steel cover design eliminate gas, odor and VOC emissions and significantly improve service/maintenance access. As no components come in contact with sludge, corrosion issues are significantly limited and the equipment features an increased life expectancy and a trouble-free operation.

Ovivo® Buoyant Steel Cover (Type B)
The Ovivo Type B covers use radial beam design structure, including a peripheral buoyant chamber. The cover floats directly on the digester content. Precast concrete ballast blocks are provided to maintain a specified gas pressure. A major portion of the buoyant volume which keeps the cover afloat is located at the cover periphery; this feature provides an excellent resistance to tipping. A slide guide system will provide vertical movement preventing rotation or binding.

The EZ-RECT™ cover erection system is a feature that is available with most digester covers. Ovivo will provide the digester cover with cover plate/radial beam sections, pre-assembled and pre-welded, to facilitate the overall assembly and erection of the cover on site. Each assembly typically consists of two (2) beams and one (1) cover plate.

Ovivo offers this option to reduce the amount of field welding required to erect a cover of significant diameter. This will reduce the total amount of field welding for the digester steel cover. Furthermore, this will reduce the number of pieces to be handled during erection.

Cover erection is completed in five steps:

  1. Side Sheet Assmbly
  2. Center Ring and Erection Beam Installation
  3. EZ-Rect Cover Plate Assembly Installation
  4. Remaining Cover Plate Installation
  5. Manholes, Spools, Tubes, Etc., Installation

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